This invention relates to apparatus and method for measuring and dispensing constant weight portions of material especially but not solely of fine-cut long-stranded hand rolling or pipe tobacco for subsequent packing, in particular to means for gauging a stream of tobacco and operating a cut off to produce accurate weight portions without the need for add back.
Such an apparatus has been disclosed and claimed in our British Pat. No. 1,446,583 and comprises means for feeding material through a measuring region, a source of radiation and a radiation detector positioned adjacent and on opposite sides of said measuring region for producing a signal representative of the flow rate of said material through said measuring region, means for integrating said signal with respect to time to give a value proportional to the total weight of material which has been fed through the measuring region, means for separating the material which has been fed through the measuring region from the remainder thereof, and means for initiating the separation after said integrated value reaches a value corresponding to said predetermined weight.
The separated portions of material are discharged from the measuring region at irregular intervals due to the variation in the density of the material being fed to the measuring region. In order to accommodate this irregularity, a conveyor system (see item 152 of 1,446,583) which delivers the cut portions to a packing machine is provided with a series of trucks which are carried by pawls which automatically engage and disengage the trucks. The pawls are positioned at regular intervals along the chain which is driven by the packer so that the arrival of the trucks at the packer where they tip their contents, is synchronised with the packing movement. In order to accommodate irregular timing of the delivered portions, the trucks are disengaged from the pawls on the chain at a filling point and are moved after filling to a position where they re-engage the pawls. This requirement for disengagement and engagement of the trucks on the pawls necessitates complexity in the design of the conveyor.